The most recent laboratory rate coefficients for the reactions of N2(A3&Sgr;u+) with O(3P) and O2 are used to determine atomic oxygen concentrations in the lower ionosphere from previously published measurements of the quenching of auroral N2(A3&Sgr;u+). It is shown that the derived atomic oxygen concentrations are in good agreement with those of the CIRA 72 model atmosphere in the 100-160 km altitude range, and not significantly smaller as has been previously suggested.